Blood pressure pattern among blood donors exposed to SARS‐CoV‐2 in Luanda, Angola: A retrospective study

Abstract Background and Aims SARS‐CoV‐2 infection is a public health concern. Several aspects related to the pattern of infection remain unclear. This study aimed to investigate the blood pressure pattern among blood donors exposed to SARS‐CoV‐2 in Luanda, Angola, a sub‐Saharan African country. Methods We performed a retrospective analysis containing 343 blood donors from December 2019 to September 2020. Parametric tests compared means while χ 2 and logistic regression checked features associated with high blood pressure and were considered significant when p < 0.05. Results The mean age of blood donors was 32.2 ± 8.81 years (ranging from 18 to 61 years) and 93% of the men's gender. Overall, 4.7% of the studied population had been exposed to SARS‐CoV‐2. High blood pressure prevalence increased from unexposed to exposed SARS‐CoV‐2 (6.7%–18.8%, p = 0.071). SARS‐CoV‐2 exposure increase systole (131 ± 12.2 mmHg to 136 ± 14.2 mmHg, p = 0.098), diastole (79.9 ± 9.53 mmHg to 84.2 ± 12.7 mmHg, p = 0.086), pulse in beats per minute (72.0 ± 11.1 to 73.7 ± 8.50, p = 0.553), and decrease donating time (6.31 ± 3.72 min to 5.48 ± 1.61 min, p = 0.371). Chances of having high blood pressure were high [OR: 3.20 (95% confidence interval [CI]: 0.85–12.1), p = 0.086] in exposed SARS‐CoV‐2. Donors exposed to SARS‐CoV‐2 with abnormal donation time increased from the donor up to 40 years to over 40 years (from 35.7% to 50%, p = 0.696). The mean systolic, diastolic, and pulse pressure were higher for non‐O donors (p > 0.05). A significant link was observed, between the Rhesus factor and blood pressure status (p = 0.032). Conclusion We showed important variations in blood pressure indices of the Angolan population exposed to SARS‐CoV‐2. Older age and non‐O blood groups appear to be important biological factors for SARS‐CoV‐2 infection, as well as the risk of developing cardiovascular disease after or during SARS‐CoV‐2 exposure. Further studies assessing the impact on cardiovascular functions with ongoing or long‐term SARS‐CoV‐2 exposure in individuals from resource‐limited countries should be considered.

Further studies assessing the impact on cardiovascular functions with ongoing or long-term SARS-CoV-2 exposure in individuals from resource-limited countries should be considered.

K E Y W O R D S
ABO/Rh blood groups, Angola, hypertension, Luanda, SARS-CoV-2 1 | INTRODUCTION SARS-CoV-2 is currently considered a major concern for global public health due to its large social and economic repercussions as well as impacts on the stability of health systems, mainly in low-and middleincome countries (LMICs). 1,2 Currently, more than 600 million individuals were infected and more than 6.5 million deaths have been reported globally, of these, more than 100 thousand infections and about 2000 deaths were reported in Angola. 3 As expected, LMICs tend to be less responsive to the COVID-19 pandemic, especially in the aspects of diagnosis, dissemination, and molecular evolution at the community level. [4][5][6][7] On the other hand, high-income countries have shown high rates of infection, spread, mortality, and molecular variability of the SARS-CoV-2, mainly due to the installation of the virus in the older population, as reported by several studies, which, in turn, these aged infected cannot, from an immunological point of view, fight the infection naturally. 8 As a result, high mortality has been observed in the adult population or with a history of any chronic disease, such as hypertension, diabetes, or even cardiovascular disease that is becoming increasingly prevalent in sub-Saharan Africa (SSA) although limited data still exist from Africa on the effects of these noncommunicable diseases (NCDs) on COVID-19. [9][10][11][12] In recent decades, resource-limited countries have witnessed a significant shift towards increased blood pressure, and yet only one in three people are aware of their hypertension status ensuring their blood pressure is controlled resulting in increased costs to the local healthcare system. 13 A previous study noted discordant patterns in the relationship between COVID- 19 and cardiovascular disease or hypertension in sub-Saharan African countries. 14 In the context of a global pandemic such as COVID-19, with the increase in cases and deaths reported worldwide, many people living with NCDs in African countries might find it more difficult to access care as most of the available resources have been diverted to focus on the pandemic which has caused disruptions in NCD management, with significant implications for NCDs and the continuity of care in Sub-Saharan Africa after the era of COVID-19. 15 The medical and scientific community have continually made strenuous efforts to gain a deeper understanding of the disease, mainly by identifying the pattern of SARS-CoV-2 infection, transmission, and COVID-19 severity in populations from different settings. 8 Even though, as the virus spreads in different regions and populations with different features, several aspects related to the pattern of infection remain unclear and need to be studied, such as the distribution pattern of blood pressure indices in a population exposed to SARS-CoV-2 short or long term. 16 Previous studies have shown that high systolic blood pressure on hospital admission is an important risk factor in models that predict the outcome of patients with COVID-19. [17][18][19][20] To the best of our knowledge, there is no published study assessing the blood pressure pattern and possibly biological and nonbiological factors that may be related to changes in blood pressure in the exposed SARS-CoV-2 population from Angola. Therefore, this study aimed to investigate for the first time the putative profile of blood pressure in an asymptomatic population exposed to SARS-CoV-2 and residents in Luanda, the capital city of Angola, a sub-Saharan African country, to present strategies to expand clinical and epidemiological management as well as to reduce the risk of developing cardiovascular disease in individuals exposed to SARS-CoV-2 in Angola. Being a retrospective study, the informed agreement was waived by the National Ethics Committee of the Angolan MoH.

| Data acquisition and description
A structured questionnaire was used to gather data such as age, gender, and donation duration in minutes from databases of the healthcare units. Frozen blood plasma samples were used to test the infectious disease markers such as anti-SARS-CoV-2 antibody screening. Specimens were thawed and an estimated 5 mL aliquot of the blood plasma was used for the qualitative detection of IgM/ IgG antibodies against SARS-CoV-2 with enzyme-linked fluorescence assays (bioMérieux SA), commercially available, following the manufacturer's instructions. Positive and negative control supplied by the manufacturer has been incorporated into all the reactions.
Findings were grouped as follows: past infection (IgG+/IgM-) and recent infection (IgG-/IgM+ or IgG+/IgM+). ABO/Rh blood-group phenotypes determination was conducted using blood grouping antisera and diagnostic kits (Lorne Laboratories Limited), according to the manufacturer's instructions. 21 The following ABO blood groups A, B, and AB were categorized as non-O. We used the Trucare KD-558BR arm manometer (Andon Health CO., Ltd) for the measurement of systolic, diastolic, and pulse blood pressure. 22 The entire blood pressure monitor process, as well as the interpretation of systolic, diastolic, and pulse findings, were conducted following the manufacturer's instructions. 22 For this study, we considered the CDC guidelines and findings from previous studies, which show that the blood donation candidate can only be approved when at least the maximum systolic blood pressure is below 140 mmHg and the diastolic below 90 mmHg. 23,24 Consequently, high systolic blood pressure was taken into consideration when the values were higher than 140 mmHg, while diastolic pressure was considered elevated when the values were higher than 90 mmHg. Candidates who have had high blood pressure above 140/90 mmHg have been grouped into the high or abnormal blood pressure category. Normal blood donation time in this study was considered to be between 6 and 10 min while the pulse pressure was between 60 and 100 beats per minute.

| Statistical analysis
Statistical analyses were performed in SPSS v28 (IBM SPSS Statistics). The descriptive analysis was introduced as frequencies and percentages. The normal data distribution was presented as mean and standard deviation (SD). Independent-sample T tests were used for comparing mean values. The categorical variables were dichotomized and analyzed with the χ 2 test and univariate logistic regression with an appropriate 95% confidence interval (CI). The reported p value is two-tailed and was considered to be statistically significant when p < 0.05.

| RESULTS
3.1 | Blood pressure patterns among exposed and nonexposed to SARS-CoV-2 The pattern of blood pressure in blood donors exposed to and unexposed to SARS-CoV-2 is shown in Table 1. A total of 343 blood donors fulfilled the inclusion criteria and formed part of the analyses. in the study had a history of being exposed to SARS-CoV-2, either past (4.7%) or recent (3.5%) infections. The mean in systolic pressure (131 ± 12.2 mmHg to 136 ± 14.2 mmHg, p = 0.098), diastolic pressure (79.9 ± 9.53 mmHg to 84.2 ± 12.7 mmHg, p = 0.086), and pulse in beast per minutes (72.0 ± 11.1 to 73.7 ± 8.50, p = 0.553) increases with exposure to SARS-CoV-2, even though any statistical relevance (p > 0.05). Also, a nonsignificant reduction was noted in the duration of donating time in minutes (6.31 ± 3.72 to 5.48 ± 1.61, p = 0.371). No significant relationship has been observed between exposure to SARS-CoV-2 and blood pressure status, pulse, or duration of blood donation (p > 0.05). Nevertheless, the prevalence of blood donors with high blood pressure has risen from unexposed to exposed to SARS-CoV-2 (6.7%-18.8%, p = 0.071). The mean values of systolic, diastolic, and pulse blood pressure, were higher for donors with past infection, although no statistical significance (p > 0.05). Also, no significant relationship was found between the past infection caused by SARS-CoV-2 with blood pressure status, pulse, or duration of blood donation. Conversely, marked increases in mean systolic (131 ± 12.2 mmHg to 143 ± 9.96 mmHg, p = 0.022) and diastolic (80.0 ± 9.64 mmHg to 89.8 ± 11.6 mmHg, p = 0.024) blood pressure were observed in the donors with recent SARS-CoV-2 infection.
Additionally, a statistically significant relationship was found between recent SARS-CoV-2 infection and blood pressure status, being checked as an increase significantly by around six times (from 6.8% to 40%, p = 0.005). Moreover, the prevalence of donors with abnormal donation duration increased with recent infection by around two times, from 31% to 60%, although this is not significant (p = 0.161). Chances of a blood donor exposed to the SARS-CoV-2 having high blood pressure were high [OR: 3.20 (95% CI: 0.85-12.1), p = 0.086] in comparison to unexposed donors. Furthermore, the probability of the donation duration being abnormal was high T A B L E 1 Blood pressure distribution pattern among exposed and nonexposed subjects to SARS-CoV-2 in Luanda, Angola.

| DISCUSSION
To the best of our knowledge, this study provides the first possible evidence that individuals exposed to SARS-CoV-2 infection are prone to developing cardiovascular disease in Luanda, the capital city of Angola. Generally, elevations in blood pressure values have been identified as an independent factor in the development of cardiovascular disease or end-stage renal disease. We showed that individuals exposed to SARS-CoV-2 have blood pressure levels of around 136/ 84 mmHg. Although it is within the accepted values as normal, 25 these values were high in comparison to the average of the healthy population and not exposed to SARS-CoV-2 in Angola, which was around 131/80. These findings showed that the need for interventions to prevent cardiovascular or kidney disease should focus not only on individuals who have blood pressure above 140/90, which is globally considered high but also pay attention to individuals with normal high blood pressure values, especially those exposed to viral infectious diseases, such as the SARS-CoV-2 because they present high mean values when compared to the mean values of the population not exposed to viral infectious diseases. These results also emphasize that blood pressure quintile (I. Lowest, II. Second, III. Third, IV. Fourth, and V. Highest) definition studies in the Angolan population exposed or not to viral infectious diseases as well as the population with or without the presence of chronic diseases should be carried out in different regions, to assist Angolan clinicians in decision-making to prevent the progression of cases of cardiovascular or renal diseases in the population. 25,26 It is worth mentioning that individuals with active or recent infection with positive IgM antibodies against SARS-CoV-2 had a mean blood pressure of around 143/90 mmHg. Furthermore, the prevalence of individuals with high blood pressure status increases significantly (6.8%-40%, p = 0.005) with the presence of active or recent SARS-CoV-2 infection (Table 1). We cannot rule out the possibility that these individuals already had a history of high blood pressure before they were exposed to SARS- observed that the risk of an exposed individual with recent or past SARS-CoV-2 infection to developing high blood pressure is 3.2 times (95% CI: 0.85-12.1, p = 0.086), compared to the population not exposed to SARS-CoV-2. These results suggest that the clinical staff should closely monitor blood pressure indices in an individual with a recent infection or do a clinical follow-up of blood pressure in individuals exposed to SARS-CoV-2. We showed that the increase in blood pressure also implies an increase in the pulse blood pressure and as a result of the increase in the pulse blood pressure, we will have reduced blood donation time ( Table 1). As we expected, we Furthermore, we showed that individuals exposed to SARS-CoV-2 might have a blood donation time 1.34 times higher (95% CI: 0.48-3.79, p = 0.578), compared to the unexposed population.
Identification of individuals at high risk of developing cardiovascular disease from the analysis of the time of blood donation needs to be explored in future studies and the information generated will be crucial to immediately assist in the management of blood donors with abnormal donation time. Also, the relationship between the psychosocial status of the blood donor with changes in blood pressure and the time of donation needs to be explored in the future.
Previous studies have shown that there appears to be an association between ABO/Rh blood groups and SARS-CoV-2 infection. [31][32][33] The observation that the population exposed to SARS-CoV-2 with blood group O did not exceed 50% (  Abbreviations: BPM, beats per minute; DBP, diastolic blood pressure; SBP, systolic blood pressure. treatment in the hospital and artificial respiration compared to other non-O blood groups. [35][36][37][38] We previously demonstrated a lower SARS-CoV-2 positivity in blood group O individuals as well as a lower risk of infection compared to non-O individuals. 39 The affinity between SARS-CoV-2 with the cells of the respiratory or gut system as a function of the host's ABO/Rh blood group is not yet clarified and is the subject of further investigation in the future. Furthermore, has no scientific evidence showing whether the blood pressure of the population exposed to SARS-CoV-2 changes according to ABO/Rh blood groups. Even though, we already expected that blood donors over 40 years of age would have the highest mean blood pressure or pulse and the shortest donation time (  39 which, in addition to increasing its prevalence, has been associated with the risk of arterial hypertension in the Angolan population. 42,43 There are important limitations to be considered when interpreting the results of this study. First, the small sample size of individuals exposed to SARS-CoV-2 limits our power to analyze and extrapolate the results to the whole population of Luanda, the capital city of Angola. Second, the effect of blood pressure changes was not taken into account for the different SARS-CoV-2 strains, which also deserves investigation in the future. Third, information about blood pressure changes during or after at least 6 months since SARS-CoV-2 exposure was not considered in this study and this should also be considered in future studies. Fourth, more sociodemographic (e.g., area of residence, occupation, educational level, and monthly income), behavioral (e.g., alcoholism, tobacco, and physical activities), and clinical (e.g., family history of chronic illness) information, were not investigated in this study. Therefore, future studies of this nature should also consider the possibility of including these variables that have considerable weight from the point of view of epidemiology and dissemination of infectious agents. Finally, the clinical outcome of individuals exposed to SARS-CoV-2 and who had high blood pressure was not recorded, therefore, our study presents very informative data and has many policy implications in the area of public health with the recent outbreak of the global pandemic. Angola, which could help to give a new direction to the management of individuals exposed to SARS-CoV-2 in Angola.

| CONCLUSION
Our results showed significant variations in blood pressure indices of the Angolan population exposed to SARS-CoV-2. Individuals over 40 years and exposed to SARS-CoV-2 presented high blood pressure.
Moreover, non-O blood group individuals presented higher positivity to SARS-CoV-2 and high mean values of systolic, diastolic, and pulse blood pressure. This is a very preliminary study that suggests that careful follow-up could be necessary for patients who have